As a technology for chemically reforming fat and oil, the technology of interchanging esters in or among the molecules of fat and oil, that is, recombining fatty acid to reform fat and oil has been widely utilized along with the reforming technology based on the hydrogenation. The reforming technology of interchanging esters has been applied to, for example, the production of edible oils.
The interesterified oils that are formed by the above reforming are, usually, colored and from which the residual catalyst and the by-produced soaps must be removed. For this purpose, a decolorizing treatment has been conducted by using a variety of adsorbents.
For instance, a patent document 1 discloses an art of interesterifying animal/vegetable fat and oil, readily adding water thereto to thereby inactivate the catalyst and liberate the by-produced soaps as hydrates, removing the soaps by centrifugation or filtration, and removing the remaining soaps from the interesterified oils by washing with water.
Further, a patent document 2 discloses an art of adding 3% of water to an interesterified oil to liberate the soaps as hydrates, removing the soaps by centrifugation, conducting the washing with water and, thereafter, conducting the decolorizing treatment by using an adsorbent.    Patent document 1: JP-B-57-61797 (page 1, col. 1, line 2 from bottom to col. 2, line 6)    Patent document 2: JP-B-53-38084 (page 3, col. 6, lines 2-9)